In conventional sheet-feed rotary printing presses, it is common to employ sheet-feed, turning or transfer drums to convey and guide the freshly printed sheets from one impression cylinder to another or to a subsequent printing or delivery station. When the rotating surface of the drum engages the freshly printed surface of the sheet smearing of the ink frequently occurs due to the slight differential speed of the sheet and the supporting drum surface.
Sheet transfer and turning drums including a plurality of rod supported rollers on their peripheries are known in the prior art as shown in GB Pat. No. 972,487 and U.S. Pat. No. 4,846,062. One disadvantage of these drum arrangements, however, is that unless the peripheral rollers and/or rods are adjusted axially so the rollers engage print free spaces on the sheets, ink smearing and smudging of the printed images still frequently occurs.
In U.S. Pat. No. 3,054,348 another type of sheet-feed drum is disclosed having a peripheral surface formed by a plurality of brush rings having the same diameter as the drum and disposed in side-by-side, spaced-apart relation along the drum axis. The brush rings are secured to discs rotatably disposed on the drum shaft and the freshly-printed sheets are supported and conveyed on a number of bristles of the brush rings. However, because relative motion still occurs between the sheet and the brush ring, particularly when chain gripper take-off conveyors are used, smudging and scratching of the printed image by the ring brush bristles cannot be completely avoided.